What makes the Web so popular?
Ease of use, thanks to the graphical user interface and point-and-click
features. Navigation is non-linear and non-hierarchical. The hypertext
links allows you to jump from one section, page, file, or site to another
in any direction as you please. The variety of file types makes it interactive
and multimedia. Once again, the hypertext links to different file types
allows you to perform any task such as read articles and documents; write
an e-mail; view pictures or computer-generated animation; watch a video
clip; listen to music and radio; take an online test; fill out a survey
form; and download files and software.
This section will help you identify the most common file types on the
Web by their file names and extensions on the URL. You already know that
a URL that ends with "html" is a web page.
Common File Types
In general, on the Internet you'll find two kinds of files: ASCII
(American Standard Code for Information Interchange) and binary.
These are also the commonly used ways to transfer data by FTP. ASCII files
are often referred to as "askee-text" because these are simple text files,
with the computer codes defining the alphabetical characters. Examples
of ASCII file types are plain text files, HTML, and most e-mail files.
Binary file types are more sophisticated in that the codes also carry
formatting and graphical information, like spreadsheets, sound, images,
video, animation, and Adobe Acrobat's PDF (Portable Document File). They
are called binary because the codes are in 0's and 1's.
Text
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Plain text files are identified by the filename extension of .txt.
The beauty of plain text files is they can be translated by any text editor
and word processor program, whether your computer has Notepad®, Microsoft
Word®, or WordPerfect.®
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HTML. Files in this format are called Web pages and have extensions
of either html or htm. The formatting instructions that tell
the browser how to display the page are called tags. For example,
to align a sentence on the center, the sentence will begin with <CENTER>
and end with </CENTER>.
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DOC and WPD. These are the file extensions of the most common word
processor formats, namely, Microsoft Word® for .doc and WordPerfect®
for .wpd. Since web browsers do not typically support this format,
your computer will be asked or prompted by what application to open or
save this file.
Image
There are at least 10 computer graphic formats out there but the two types
you will often come across in the Web are .gif developed by Compuserve
and .jpeg by the Joint Photographic Experts Group.
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Gif (pronounced "jif") images are efficient in that there is no
distortion when during compression and decompression. Thus, they take up
less kilobyte space and therefore load faster, but are limited to 256 colors
only.
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JPEG (pronounced "jay-peg") can contain a million colors and are
ideal for photos or pictures. JPEG graphics usually don't support transparent
backgrounds and shadow features. Some JPEG files have extensions of .jpg.
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The World Wide Web Consortium (W3C) has introduced .png.
PNG stands for Portable Network Graphics and was designed to be fast-loading,
efficient, and patent-free. Newer websites will likely use this format.
Sound/Audio
There are .wav, .mid., and .ra audio files. Each format requires
a different software player, fortunately, most of these come with your
multimedia PC, or built-in with your browser, or may be downloaded
at no or minimal cost. These players have panel controls to stop, play,
and pause using the same symbols found on regular cassette players and
VCR. The more elaborate ones have volume control, counter, and channel
selector. You can even choose and download custom-designed "skins" if you
want, say, a zebra stripe theme or metallic look for your control panel.
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Waveform is the most common, and both Netscape and Internet Explorer
are able to play this audio file type. Click
here to hear a two-second wav file called "tribalb1.wav"
from http://bigsamples.free.fr/ (guess what country this website originated!).
Move your mouse over the link "click here" and see the complete URL with
the filename and .wav extension of this sample file appear on the bottom
of your window. Many sound effects such as glass breaking, horn blowing,
and animal sounds are in wave format.
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MIDI, which stands for Musical Instrument Digital Interface, is
a music synthesizer format that takes up a lot less space than waveform.
Click
here to listen to a midi version of Mozart's "Rondo Ala
Turk" as performed by Richard
A. James, who graciously gave permission for the use of this music
file here.
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RealNetworks.com developed what is called "real-time audio streaming"
which allows the Internet to function like a radio, broadcasting music
and voices in real time. There are several Internet radios and channels
now playing music and talk programs in different countries. You can listen
to a channel that plays nothing but classical music while you are working
on the computer, or hear a live concert, or listen to an interview with
a famous rock star. Visit their website at
http://www.real.com/
to
download a copy of RealJukebox, their latest audio software. This software
also allows you to play MP3 music files.
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MP3 is short for MPEG-1 Layer-3, a technology that compresses digital
audio files like CD music without losing sound quality. Its flexible
format makes the MP3 easy to download, copy, and play on any sequence you
want. Sometimes called MPEG Audio Layer 3 to differentiate it from MPEG
digital video files, otherwise, the rest of the world knows it by its more
popular, rather, controversial name of MP3. Visit the software download
page of MP3.com to choose your MP3 player at
http://software.mp3.com/software,
each one comes with a link to reviews.
Video
Both Netscape Communicator and Internet Explorer have built-in players
for video file types .mpg, .avi, and .mov and .qt.
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AVI ("audio video interleave") was developed by Microsoft and is,
naturally, the most common format in Windows. Although there are less and
less video files in this format now it still comes in handy at times.
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MOV and QuickTime are products of Apple. The beauty of QuickTime
is it can run on either Mac or Windows.Go to
http://www.apple.com/quicktime/download/
to download the latest player and take a tour.
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MPEG, developed by the Motion Picture Experts Group, is an
emerging digital video format with applications on the Web, CDs, cable
TV, direct satellite broadcasts, and high-definition television (HDTV).
It is endorsed by the International Standards Organization (ISO) that formed
the MPEG committee, and recognized by over 70 companies including IBM,
Apple, Philips, and Sony.
Animation
Animation helps make a page appear more alive, although
too much of it can cause headaches. There are animated gifs such as the
ones used in this site, i.e. rotating apple. Dynamic HTML (DHTML),
also creates special effects that makes pages more interactive and, yes,
dynamic. A programming language like JavaScript can create DHTML effects
like pop-up windows, scrolling text, buttons or images that change colors
when your mouse moves over them, and in this particular page, the slideshow
on the upper left corner.
You will also find computer-generated animation on
the Web in QuickTime and MPEG formats. Internet.com's
webpoedia
differentiates video as a file of moving images that is broken down in
frames, while animation consists of "independent pictures and puts them
together to form the illusion of continuous motion."
Video & Animation Samples
These samples, unless otherwise specified, are copyright-free
materials obtained from the NASA Multimedia Gallery at
http://www.nasa.gov.
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